dmjalund Posted November 11, 2020 Report Share Posted November 11, 2020 3 hours ago, Cancer said: Arecibo has had another cable snap in the last couple of days. their warranty must have just run out Quote Link to comment Share on other sites More sharing options...
Cancer Posted November 11, 2020 Report Share Posted November 11, 2020 Well, when you have a small number of cables supporting a fixed amount of mass, when you lose one cable the strain gets redistributed among the remaining cables, which is sort of a recipe for losing more. I have seen comments suspecting the anchor points for the cables, not merely the cables themselves, were damaged by the hurricane stresses. And, lots of things in Puerto Rico took not-always-obvious damage in the 2017 hurricane, and federal help has not been forthcoming at anything like the level that comes for states. It is appalling how much of the crucial electrical utility infrastructure in the region around the observatory was rebuilt by observatory staff after the hurricane, because they were on the ground there and had the know-how (though not usually the materials and tools), and in 2017 the federal political apparatus was not interested in sending aid to a Spanish-speaking area, even if it has been a US dependency for over a century. Lee 1 Quote Link to comment Share on other sites More sharing options...
tkdguy Posted November 11, 2020 Author Report Share Posted November 11, 2020 SpaceX to send astronauts to ISS Launch date is November 14, at 7:49 pm EST Quote Link to comment Share on other sites More sharing options...
tkdguy Posted November 13, 2020 Author Report Share Posted November 13, 2020 Shooting Lasers at Eta Carinae DShomshak 1 Quote Link to comment Share on other sites More sharing options...
Cancer Posted November 13, 2020 Report Share Posted November 13, 2020 Why shoot at that? Just going for style points after the outcome is assured? DShomshak 1 Quote Link to comment Share on other sites More sharing options...
tkdguy Posted November 13, 2020 Author Report Share Posted November 13, 2020 1 hour ago, Cancer said: Why shoot at that? Just going for style points after the outcome is assured? Possibly, since our lasers won't reach the nebula for another 7500 years. Not sure what good the experiment will do; I just reported it. Quote Link to comment Share on other sites More sharing options...
Michael Hopcroft Posted November 13, 2020 Report Share Posted November 13, 2020 1 hour ago, tkdguy said: Possibly, since our lasers won't reach the nebula for another 7500 years. Not sure what good the experiment will do; I just reported it. And am I correct in thinking it will be another 7500 years before we learn about any effect it might have had? Does anyone seriously believe homo sapiens will be around that long? Quote Link to comment Share on other sites More sharing options...
archer Posted November 14, 2020 Report Share Posted November 14, 2020 4 hours ago, tkdguy said: Possibly, since our lasers won't reach the nebula for another 7500 years. Not sure what good the experiment will do; I just reported it. So the aliens in the nebula won't think we're attacking them with low-powered lasers for another 7500 years. Good to know. Quote Link to comment Share on other sites More sharing options...
tkdguy Posted November 14, 2020 Author Report Share Posted November 14, 2020 Would lasers even be effective or even visible at that range? Even they are susceptible to the blooming effect. Quote Link to comment Share on other sites More sharing options...
Cancer Posted November 14, 2020 Report Share Posted November 14, 2020 I think that if you knew what was coming, you could detect them with instrumentation. No chance with the eyeball, no matter how big a telescope. But you;d need to know something about the lasers being fired at you, at least with 2020 technology. Quote Link to comment Share on other sites More sharing options...
novi Posted November 15, 2020 Report Share Posted November 15, 2020 On 11/12/2020 at 11:53 PM, tkdguy said: Shooting Lasers at Eta Carinae OMG! Whoever wrote this article is a mouth-breathing moron. The astronomers are just using a particular color for a laser guide star. They're only shooting it into the upper atmosphere to watch how light scatters up there. This is barely even a story aside from the pretty pictures. That author should be fired, preferably out of a cannon. Quote Link to comment Share on other sites More sharing options...
Old Man Posted November 16, 2020 Report Share Posted November 16, 2020 Crew Dragon launch in ten minutes. Quote Link to comment Share on other sites More sharing options...
tkdguy Posted November 16, 2020 Author Report Share Posted November 16, 2020 Crap, I missed the launch! Quote Link to comment Share on other sites More sharing options...
Cancer Posted November 19, 2020 Report Share Posted November 19, 2020 On 9/14/2020 at 3:12 PM, tkdguy said: Phosphines found in Venus' atmosphere Potential signs of life in Venus? On 9/15/2020 at 11:50 AM, Cancer said: The technical paper in Nature Astronomy is here. I managed to get to it this morning without a subscription, so I don't think it's behind a paywall, but YMMV. This is based on spectroscopic observations of an absorption line at about 1 millimeter wavelength. The first observation was done with the James Clerke Maxwell Telescope in 2017, and I would call that spectrum suggestive but not compelling that an absorption line was actually present. The 2019 ALMA spectrum is better but I would still hesitate to make a claim based on that. The two data sets jointly make something worth putting into the literature. Even so, it fairly cries out for confirming evidence, which probably will have to come from an atmospheric probe: I don't think it'll be possible to do better with Earthbased data for quite some time. The best takeaway from this is the whole of their main-text final paragraph ("PH3" here means PH[sub]3[/sub]: the chemical formula for phosphine. ) Terrestrial biology does produce phosphine at a rate adequate to make the feature seen in the millimeter spectra. Other known photochemical and geochemical processes don't. That's as strong a statement in favor of life as can be made from these data, IMO. OTOH, I am not convinced that the identification of this single spectral line as being due to phosphine is bulletproof; and even if it is, while a particularly implausible assumption about a biosphere producing PH3 can produce the observed feature, that's a really bad reason to think of this as evidence for life there. Earlier this week came a note backpedaling on the phosphine claim; some calibration errors in one dataset, and then it seems that the feature identified as PH3 is perhaps better explained as a blend of a couple of S02 lines ... and SO2 is already known to be important in Venus's atmosphere. Though I didn't know abotu the calibration issues, the alternative identification for the spectral feature is towards the top of my list of reasons I was pretty skeptical of this stuff in the first place. tkdguy and DShomshak 2 Quote Link to comment Share on other sites More sharing options...
tkdguy Posted November 19, 2020 Author Report Share Posted November 19, 2020 Arecibo telescope to be decommissioned Cancer and DShomshak 2 Quote Link to comment Share on other sites More sharing options...
dmjalund Posted November 20, 2020 Report Share Posted November 20, 2020 Venus has spectral features? Does this mean that Venus is haunted? Quote Link to comment Share on other sites More sharing options...
tkdguy Posted November 20, 2020 Author Report Share Posted November 20, 2020 Conflicting opinions about colonizing Mars: Elon Musk's Vision Werner Herzog's Critique Quote Link to comment Share on other sites More sharing options...
tkdguy Posted November 21, 2020 Author Report Share Posted November 21, 2020 Here's an instance where my Astronomy major and my Classical Archaeology minor cross over. Temple restoration reveals previously unknown ancient Egyptian constellations DShomshak and Cancer 2 Quote Link to comment Share on other sites More sharing options...
dmjalund Posted November 21, 2020 Report Share Posted November 21, 2020 1 hour ago, tkdguy said: Here's an instance where my Astronomy major and my Classical Archaeology minor cross over. Temple restoration reveals previously unknown ancient Egyptian constellations Can they be used to create gate addresses? Quote Link to comment Share on other sites More sharing options...
tkdguy Posted November 21, 2020 Author Report Share Posted November 21, 2020 30 minutes ago, dmjalund said: Can they be used to create gate addresses? I'll ask Richard Dean Anderson about it next time I talk to him. Amorkca 1 Quote Link to comment Share on other sites More sharing options...
pinecone Posted November 21, 2020 Report Share Posted November 21, 2020 More mysteries about dark matter. tkdguy 1 Quote Link to comment Share on other sites More sharing options...
Hedgehobbit Posted November 22, 2020 Report Share Posted November 22, 2020 On 11/20/2020 at 5:42 PM, tkdguy said: Werner Herzog's Critique You can sum up Herzog's critique as "not an argument". To claim that going to Mars is obscene because fascism and communism existed is completely bonkers. Besides, Elon Musk is destined to go to Mars, as the leader of Mars has been called "The Elon" since 1952. Amorkca and pinecone 1 1 Quote Link to comment Share on other sites More sharing options...
tkdguy Posted November 24, 2020 Author Report Share Posted November 24, 2020 We've detected signals in space, but they look all too familiar. Quote Link to comment Share on other sites More sharing options...
pinecone Posted November 25, 2020 Report Share Posted November 25, 2020 This is a fun video on a new take on space warping. It is not yet peer reviewed. There are links for the Math parts as well. tkdguy 1 Quote Link to comment Share on other sites More sharing options...
Hedgehobbit Posted November 25, 2020 Report Share Posted November 25, 2020 2 hours ago, pinecone said: This is a fun video on a new take on space warping. It is not yet peer reviewed. There are links for the Math parts as well. A video about warp drive that has an X-Wing in the thumbnail .... Seriously!?! Quote Link to comment Share on other sites More sharing options...
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